From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3C9AFC4360C for ; Mon, 12 Apr 2021 16:50:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F27F9611C9 for ; Mon, 12 Apr 2021 16:50:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343658AbhDLQuA (ORCPT ); Mon, 12 Apr 2021 12:50:00 -0400 Received: from mail.pqgruber.com ([52.59.78.55]:33104 "EHLO mail.pqgruber.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345363AbhDLQrO (ORCPT ); Mon, 12 Apr 2021 12:47:14 -0400 Received: from workstation.tuxnet (213-47-165-233.cable.dynamic.surfer.at [213.47.165.233]) by mail.pqgruber.com (Postfix) with ESMTPSA id 3A59AC725C8; Mon, 12 Apr 2021 18:46:53 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pqgruber.com; s=mail; t=1618246013; bh=ddZOwCcmLSLlpehTOdB6y2QZnRm5env2RjYzgjkBfGs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hCCSXkcvmf3hDLc942ft97uWA4vXCnETVp35x/UuDWMbKYm1EYubMaM4ZBhheRinZ MAWgXpViB1EfLMzohLaHIwp0UB82JZaIHrmLcjWCYkjeBVgCTSB1WL+LGkYZYe0StY lQUkmivF9qcLTZEKXdDP8GzFrWPPdNaD7Thkui54= Date: Mon, 12 Apr 2021 18:46:51 +0200 From: Clemens Gruber To: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Cc: linux-pwm@vger.kernel.org, Thierry Reding , Sven Van Asbroeck , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Rob Herring Subject: Re: [PATCH v8 4/8] dt-bindings: pwm: Support new PWM_USAGE_POWER flag Message-ID: References: <20210412132745.76609-1-clemens.gruber@pqgruber.com> <20210412132745.76609-4-clemens.gruber@pqgruber.com> <20210412162723.7hlhgqp6wlfbkeky@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210412162723.7hlhgqp6wlfbkeky@pengutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 12, 2021 at 06:27:23PM +0200, Uwe Kleine-König wrote: > On Mon, Apr 12, 2021 at 03:27:41PM +0200, Clemens Gruber wrote: > > Add the flag and corresponding documentation for PWM_USAGE_POWER. > > My concern here in the previous round was that PWM_USAGE_POWER isn't a > name that intuitively suggests its semantic. Do you disagree? No. It is more abstract and requires documentation. But I also didn't want to waste too much time on discussing names, so I used Thierry's suggestion. I guess we need his input on this subject. I can live both with PWM_ALLOW_PHASE_SHIFTING and PWM_USAGE_POWER, as long as it is documented well enough. > > > Cc: Rob Herring > > Signed-off-by: Clemens Gruber > > --- > > Documentation/devicetree/bindings/pwm/pwm.txt | 3 +++ > > include/dt-bindings/pwm/pwm.h | 1 + > > 2 files changed, 4 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt b/Documentation/devicetree/bindings/pwm/pwm.txt > > index 084886bd721e..fe3a28f887c0 100644 > > --- a/Documentation/devicetree/bindings/pwm/pwm.txt > > +++ b/Documentation/devicetree/bindings/pwm/pwm.txt > > @@ -46,6 +46,9 @@ period in nanoseconds. > > Optionally, the pwm-specifier can encode a number of flags (defined in > > ) in a third cell: > > - PWM_POLARITY_INVERTED: invert the PWM signal polarity > > +- PWM_USAGE_POWER: Only care about the power output of the signal. This > > + allows drivers (if supported) to optimize the signals, for example to > > + improve EMI and reduce current spikes. > > IMHO there are too many open questions about which freedom this gives to > the lowlevel driver. If the consumer requests .duty_cycle = 25ns + > .period = 100ns, can the driver provide .duty_cycle = 25s + .period = > 100s which nominally has the same power output? Let's not introduce more > ambiguity than there already is. > > This is a NAck. > > Best regards > Uwe > > -- > Pengutronix e.K. | Uwe Kleine-König | > Industrial Linux Solutions | https://www.pengutronix.de/ |